What document does DSS publish to change or clarify existing policy requirements in the NISPOM?

The correct choice is the Industrial Security Letter (ISL), which serves as a mechanism for the Defense Security Service (DSS) to convey important updates, changes, or clarifications concerning policy requirements within the National Industrial Security Program Operating Manual (NISPOM). The ISL provides the necessary guidance to industry partners to ensure they are compliant with evolving security standards and practices.

This instrument is crucial for maintaining awareness and understanding of security protocols, ensuring that Facilities Security Officers (FSOs) and other relevant personnel within an organization are informed about any updates that could impact security operations.

While the other documents listed serve vital purposes within the realm of security, they do not fulfill the role of communicating policy updates or clarifications on existing requirements in the same way as the ISL. For instance, the Technical Security Directive (TSD) primarily focuses on specific technical security measures rather than broader policy guidelines, and the Facility Security Plan (FSP) outlines security measures for a specific facility rather than addressing changes in policy across the board. The Security Management Manual (SMM) may encompass a variety of security management practices but does not intrinsically change or clarify NISPOM policy requirements.